The subject of the present invention is a motorized reduction gear intended for functional equipment of motor vehicles, such as window lifters, sunroofs or seats.
Such a motorized reduction gear comprises a stator housed in a casing and a rotor provided with a rotor shaft bearing a commutator and passing through a rolling bearing housed in a support of a reduction gearbox. The rotor shaft is placed in the reduction gearbox and comprises a worm engaging with a gearwheel housed in the reduction gearbox, this gearing being appropriately lubricated by grease or oil. Frequently, the motorized reduction gear is placed with its rotor shaft and its rotor arranged substantially vertically.
It has been found that after a certain period of use of this motorized reduction gear, there is premature wear of the brushes sliding on the commutator because of the presence of lubricant thereon, as a result of leaks of lubricant from the internal gearing into the reduction gearbox.
This is because, given the vertical arrangement of the motorized reduction gear, the commutator and the brushes are placed below the reduction gearbox, its worm and the gearwheel. In addition, the high operating temperature of the motorized reduction gear encourages oil or grease to leak out of the reduction gearbox, between the reduction gearbox and the rolling bearing.
The object of the invention is to propose a motorized reduction gear in which any leak of lubricant from the inside of the reduction gearbox is eliminated, thus encouraging an increased longevity of the commutator brushes.
According to the invention, a seal is inserted between the bearing and the bearing support, on the side of the bearing close to the inside of the reduction gearbox.
This seal may be an O-ring or equivalent, and has a hardness appropriate to the ball-joint action of the shaft (self-alignment of the shaft with the bottom bearing of the stator).
Under these conditions, any inadvertent leak of lubricant from inside the reduction gearbox is eliminated.